code: def export_maxsplit() -> None:
      node = onnx.helper.make_node(
          "StringSplit",
          inputs=["x"],
          outputs=["substrings", "length"],
          maxsplit=2,
      )
  
      x = np.array(
          [
              ["hello world", "def.net"],
              ["o n n x", "the quick brown fox"],
          ]
      ).astype(object)
  
      substrings = np.array(
          [
              [["hello", "world", ""], ["def.net", "", ""]],
              [["o", "n", "n x"], ["the", "quick", "brown fox"]],
          ]
      ).astype(object)
  
      length = np.array([[2, 1], [3, 3]], np.int64)
  
      expect(
          node,
          inputs=[x],
          outputs=[substrings, length],
          name="test_string_split_maxsplit",
      )
  
file_path: onnx/onnx/backend/test/case/node/string_split.py
imports: import numpy
  import onnx
  from onnx.backend.test.case.base import Base
  from onnx.backend.test.case.node import expect
label_desc: Use image node_id 2 for calling the StringSplit obj's underlying member method code with example usage: obj.export_maxsplit() without return types